SAMPLING  PROCEDURES Correct sampling and labeling of petroleum prod- ucts is as important to fuels inspection as correct testing. Improper containers of poorly drawn samples or incor- rectly identified samples can cause laboratory results to be meaningless or, worse, misleading. Some cardinal rules in sampling follow: 1. The sampler’s hands or gloves must be clean. 2. A sample container must be meticulously clean. It should be thoroughly cleaned and inspected before use. Before a sample is taken, the clean container should be rinsed and flushed three times with the fuel being sampled. 3. All samples must be representative of the prod- uct being sampled. Any sample of fuel being delivered to an aircraft should be taken from the fueling nozzle and during actual fueling operations. A sample taken to test a fixed filter/separator should be taken at the filter d i s c h a r g e .  4. Each sample should be capped promptly with an approved cap. Do not use sealing wax, rubber gaskets, or caps with wax seals. 5. Each sample should be drawn from a connection in a vertical pipe run where practical. If it must be drawn from a horizontal run, the connection should be halfway between the top and the bottom of the pipe. 6. A sample should be taken with the system oper- ating at a normal and steady flow rate, if possible. 7. To prevent leakage due to increased pressure caused by thermal expansion of the product, do not fill any container above 90 percent capacity. 8. A container such as a drum should be sampled with a thief sampler and not by tilting. Be careful to remove all foreign matter from the area before the plug is removed from the drum. 9. For nozzle samples, the sample should be taken from the overwing nozzle during or immediately after the  fueling  of  an  aircraft.  A  pressure  nozzle  has  a Gammon sample connection that allows a sample to be taken while the aircraft is being fueled. Sizes of Samples The minimum size sample container for taking samples of fuel is 1 quart. This size sample is of suffi- cient size for sediment, water, and flash point tests only. For other types of tests, the sample submitted should be at least 1 gallon. A sample container for sediment and water tests must always be glass with a nonmetallic top. Identification of Samples Proper identification and accurate records of sam- ples are necessary so the test results maybe correlated with the samples submitted. The following should be used as a guide for sam- ple identification: 1. 2. 3. 4. 5. 6. Sample serial number (activity number). Type fuel (JP-5, MOGAS, and so on.). Name and location of activity. Date sample taken. Approximate time the sample was taken. Location of sample point (nozzle sample, filter number, tank number, refueler number, and so on.). 7. Quantity of material represented, if applicable. 8. Classification of sample (routine or special— see the following section). 9. Name of person taking sample. 10. Tests required. 11. Remarks. Sample  Classification Samples  are  classified  as  either  ROUTINE  or SPECIAL. ROUTINE samples are taken when no fuel problems or aircraft problems attributable to fuel are known or suspected. An example is the periodic sam- pling taken as a part of a quality surveillance program. These  samples  should  be  tested  for  sediment  and water, and for JP-5, flash point. SPECIAL samples are submitted for test because the quality of the fuel is suspected, either as the result of aircraft malfunctions or other information. SPECIAL samples should have the highest priority in handling, testing, and reporting. Container The container for drawing a visual sample should be at least 1 quart in size, round, and made of clear glass. The top should be as large as possible to aid in drawing  the  sample  without  spilling  the  fuel.  The cleaning procedures previously described under sam- pling procedures should always be earned out when you are taking a visual sample. 3-12